Switch



March '10, 1942.

"E. A. NOR'DBERG swzwcn Filed Jan. 18, 1940 O ,CZ'C C D [msf 14. Mow a g BY v ATTORNEY.

Patented Mar. 10, 1942 swrron Ernst A. Nordberg, Sharon, Mass assigno'r, by mesne assignments, to Mu, Switch Corporation,

Canton, Mass.

Application January 18, .1940, Serial No. 314,499

7 Claims.

The present invention relates to electrical switch mechanism, and more particularly to such mechanism where electrical contacts are made or broken with a snap action by a comparatively light pressure and very smallmotion of the pcrating plunger, button or lever.

In the present invention the operating key, lever, pin or button may move only a few thousandths of an inch in rapidly effecting a quick making or opening of an electrical contact with movement of the pin or button. In one form of such switch, a slotted leaf spring is used, which is bowed in at its unsupported end, usually by the electric contact plate to produce a sensitive area around the end of the slot near the supported end of the leaf spring. In this form care must be exercised to assure that the plate maintain fixed, the bowed in ends, as otherwise the spring action will change. The present invention is an improvement over this type of switch, and permits a simpler construction as well as one which is apt to be much more reliable and easier, to adjust.

The invention will be better understood from the explanation and description given in the specification below, .when taken in connection with the drawing showing an embodiment of the switch, in which:

Figure 1 shows a perspective view of the switch with the cover removed, the arrow showing the point at which pressure is applied to snap the contact end up.

Figure 2 shows a top view of Figure 1.

Figure 3 shows a cross section taken on the line3-3 of Figure 2.

Figure 4 shows a cross sectionof the adjustment detail taken on line 4-4 of Figure 2.

Figure 5 shows a side view of the switch with the cover removed wherein the dotted line shows the spring. in the up position.

Figure 6 shows the detail of the shape of the base support for holding the spring.

Figure 7 shows the detail of the original. shape of the spring without the adjustment element ap- I plied thereto.

Figure 8 shows a modification of the spring in the same corresponding view as Figure 7, and,

Figure 9 shows a modification of the supporting base for the leaf spring in the same relationship as Figure 6. Y I

Referring to the drawing in which the same parts bear the same numbers, I is the switch base which may bemade out of any suitable insulating material such as hard rubber, pressed Bakelite,

mica compounds, or other prepared insulating material. At one end the base has a built up support 2 which may be an integral part of the base or a separately attached piece. The support 5 2 has peripheral flanges at the back 3 and the sides I and 5 forming a recessed portion 6 at the center portion of the support. Two holes I and 8 extend through the back flange 3 and the base 4 and receive the bolts or screws 9 which hold the 10 leaf spring I which will presently be described, a motion of a much greater distance than the although the leafspring may be held by a single screw passing through a centrally located hole I I as indicated in Figure 9, and for this purpose the spring leaf may have a centrally located hole I2 shown dotted in Figure '7. The spring leaf H) which may be made out of Phosphor bronze or any other suitable metal is initially a flat piece or sheet having a slot I4, either tapered all the way as shown at M or only part way as shown at M, with a narrow parallel edged slot I5 errtending from the tapered slot and terminating in a circular hole It. The leaf spring may also be made of thermal bi-metal in which case it will actuate a small temperatur change independent of the operation of the pin 20. One end of the spring has holes I! and I8, spaced apart and located to position the spring symmetrically on the support 2 when the screws 9 are put through the spring for fastening the spring to the base.

In its proper position the edges of the spring about the mounting end rest on the flanges 3, 4 and 5, and since the surface of the portion 3 is concaved slightly as indicated in Figures 6 and 9, the spring when mounted against this surface is also strained slightly in making it conform to the shape of this surface. Within the area 6 which is recessed, the spring is unsupported on its bottom side and it is in this area, as indicated by the area l9 that the pin 20 acts. The other end of the leaf spring l0 may carry a contact element 2| cooperating with the contact element 22 mounted by the screws or bolts 23 passingthrough the back posts 24 mounted on the base I.

In its-lower position, the spring leaf (Figures 3 and 5) is limited-in motion by a lower support I r 25 mounted on the base I by means of the screws 26. This support may also be an electrical 'contact in which case the switch may be used as a single pole double throw switch. In the present invention the portion of .the

spring in the vicinity of the arrow is made sensitive by the adjustment of the sliding tube 21 which may be a tubular rivet 28 with spread ends 2! Spread over. washers 30. The slide 21 is mountspreads the side walls or legs 30' and 3| to the dotted line position 32, 33, indicated in Figure '7, the legs are slightly bowed so that when the end of the spring is clamped in position by screws 9,

the free end of the spring is bowed downward as shown in Figure 3 and the area under the pin 20 is convexed slightly or level, but strained, making this area unstable, so that even a slight motion downward of one-thousandth of an inch or thereabouts will immediately snap the contact I end 2| (Figure 3) upwards. The slider 21 is adjustable in the tapered slot to obtain the throw of the contact end of the spring with the desired movement and pressure of the pin 20. The concaved surface 3 concaves the fixed end of the spring thus confining and making more sensitive the sensitive area under the pin 20. Actually in the operation of the spring, a very sensitive balance exists between the fixed concaved end of the spring and the bowed out convexed section around the point of action of the pin, and the more nearly the area under the pin is flat or level, the less the motion will be to throw the contact end of the spring upwards. The action of the pin 20 in this area will be to change the surface contour of the spring at this point from convex to concave upwards, thus bowing the free end of the spring upwards. As little motion as one-thousandth of an inch will snap the free end upwards.

In the modification shown in Figure 9, besides the concavedfiange 40 and a single hole II for fixing the spring end, the side flanges 4| and 42 have projecting sections 43 and 44, thus :assuring that the surface of the fixed end of the spring is concaved upwards. Since the slider convexes the free end of the spring upwards, the sensitivearea embodies the transitional section wherein a portion may practically be level. Operation of the pin at this point will take little pressure and little motion.

A cover 45 may fit on the base I around the supports 2 and 24 and be held by pins 46 passing into holes 41 in the supports 2 and 24. The base I may be mounted in any convenient way as for instance by means of the holes ,48' and 49 and the switch terminals may be brought out on the Base grooves 50 and 5| attaching to the switch contacts through the screws 9 and 23. The pin- 20 may be operated manually or by any usual lever, relay or mechanical arrangement, the pin 20 being freely supp rted in the boss 53 in the cover 45.

When the pressure on the pin 20 is released, the leaf spring III will return .to its normal inoperative position returning the pin also to the position it had before pressure was exerted against it so that the switch will again be ready for any succeeding operation. From consideration of Figures 1, 3, and 5, it will be noted that the contact end of the spring Ill is limited in its free motion in a vertical direction by the lower or the upper contact member. members are so positioned that the spring l0 never assumes a balanced second position of equilibrium in its operated condition so that the spring will retain sufiicient restoring force, when pressure on the pin is released, to return back to its normal position. While this condition may be obtained by limiting the and throw of the spring carrying a switch contact element at one end, means fixing said spring at the other end, a slot positioned longitudinally wholly within said leaf spring and wedge means cooperating 'with said slot for bowing outward the metal at the sides of said slot and producing a longitudinal bowing of said spring including a sensitive area in the vicinity of the fixed end of said spring wherein a slight pressure thereon will cause the free end of the spring to move with a snap action,

from its bowed position in one direction to the opposite direction, and means for applying said pressure within such area.

2. In an electric switch mechanism, a leaf spring carrying a switch contact element at one end, means fixing said spring at the other end, a tapered shaped slot positioned longitudinally wholly within said leaf spring and wedging means positioned in said slot and adapted to be adjusted to the desired position for bowing outward the metal at the sides of said slot and producing a longitudinal bowing of said spring including a sensitive area in the vicinity of the fixed end of said spring wherein a slight pressure thereon will cause the free end of the spring to move with a snap action from its bowed position in one direction to the opposite direction, and means for applyingsaid pressure within such area.

3. In an electric switch mechanism, a leaf spring carrying a. switch contact element at one end, means fixing said spring at the other end including a concave support on which the fixed end of the spring rests giving said fixed end a concave shape, a tapered shaped slot positioned longitudinally wholly within said leaf spring and These contact wedging means positioned in said slot and adapted to be adjusted to the'desired position for bowing outward the metal at the'sides of said slot and producing a longitudinal bowing of said spring including a sensitive area in the vicinity of the fixed end of said spring wherein a slight pressure thereon will cause the free end ofthe spring to move with a snap action from its bowed position in one direction to the opposite direction,

and means for applying said pressure within such area.

4. In an electric switch mechanism, a leaf spring carrying a switch contact element at one end, means fixing said spring at the other end including a concave support on which the fixed end of the spring rests and a single element centrally located on said concave support for holding said spring in place. a tapered shaped slot positioned longitudinally wholly within said leaf spring and wedging means positioned in said slot and adapted to be adjusted to the desired position for bowing outward the metal at the sides of said slot and producing a longitudinal bowing of said spring including a sensitive area in the vicinity of the fixed end of said spring wherein a slight pressure thereon will cause the free end of the spring to move with a snap action from its' bowed position in one direction to the opposite direction, and means for applying said pressure within such area.

5. In an electric switch mechanism, a leaf spring carrying a switch contact element at one end, means fixing said spring at the other end including a support having a recessedcentr'al will be noted, is sometimes area surrounded by a peripheral flange on the sides and back end with respect to the position of the spring, said spring being mounted in contact with said flanges and resting thereon, a tapered shaped slot positioned longitudinally wholly within said leaf spring and wedging means positioned in said slot and adapted to be adjusted to the desired position for bowing outward the metal at the sides of said slot, and producing a longitudinal bowing of said spring including a sensitive area in the vicinity of the fixed end of the spring within said recessed central area of said support wherein a-slight pressure thereon 'will cause the free end of the spring to move with a snap action from its bowed position in one direction to the opposite direction, and-means for applying said pressure within such area.

6. In an electrical switch mechanism, a leaf spring carrying a switch contact element at one end, means fixing said spring at the other end including a support having a recessed central area surroundedby a peripheral flange having a concaved back section and sides with respect to the position of said spring, said spring being mounted in contact with said flanges and resting thereon, a tapered shaped slot positioned longitudinally wholly within said leaf spring and wedging means positioned in said slot and adapted to be adjusted to the desired position for bowing outward the metal at the sides of said slot and producing a longitudinal bowing of said spring including a sensitive area in the vicinity of the fixed end of the spring within said recessed central area of said support wherein a slight pressure thereon will cause the free end of the spring to move with a snap action from its bowed position in one direction to the opposite direction, and means for applying said presure within such area.

7. In an electrical switch mechanism, a leaf spring carrying a switch contact element at one end, means fixing said' spring at the other end including a support having a recessed central area surrounded by a peripheral flange having a concaved back section and sides with upwardly projecting portions, said spring being mounted with its end portion in contact with said flanges and resting thereon, a tapered shaped slot positioned longitudinally wholly within said leaf spring and wedging means positioned in said slot and adapted to be adjusted to thedesired position for bowing outward the metal at the sides of said slot, and producing a longitudinal bowing of said spring including a sensitive area in the vicinity of the fixed end of the spring within said recessed central area of said support wherein a slight pressure thereon will cause the free end of the spring to move with a snap action from its bowed position in one direction to the opposite direction, and means for applying said pressure within such area.

ERNST A. NORDBERG. 

